1. Field of the Invention
The present invention relates to a repair fuse box of a semiconductor device and, more specifically, to a repair fuse box having a structure in which a signal line can be drawn out from a repair fuse box without detour.
2. Discussion of Related Art
Recently, high-speed and highly integrated semiconductor devices have been developed with development of miniaturization technologies. In particular, high integration and high yield of semiconductor memory devices have been required, and in order to cope with the requirements, a redundancy technology, which improves a yield by providing redundancy circuits and repairing defective cells using the redundancy circuit, is essential.
In memory devices such as SRAM, DRAM, EPROM, and so on, redundancy circuits are provided in the semiconductor devices to prevent decrease of yields of the semiconductor devices due to process defects. The functions of the semiconductor devices are not damaged in spite of partial defects, by repairing defective cells using the provided redundancy circuits. That is, by providing a spare memory array as a redundancy circuit and switching a main memory array into the spare memory array when the main memory array is defective, decrease of production yield can be regulated.
The redundancy circuit comprises a repair address generating circuit. A conventional repair address generating circuit has a structure shown in FIG. 1, and its operation will be explained briefly as follows.
A fuse set A comprises a plurality of fuses R0 to R15.
When an enable signal Enable is in a high state, a PMOS transistor P1 is turned off, and thus its output Out holds a low state.
When the enable signal Enable is in a low state, the output Out is changed in accordance with fuse control signals Fuse <0> to Fuse <15> and cutting states of the fuses R0 to R15.
For example, when the fuse control signal Fuse <0> is in a high state and the first fuse R0 is not cut, the NMOS transistor Q0 is turned on. Then, an output of a latch 10 is in a high state, and thus an output of the inverter I1 turns to a low state, so that the output Out turns to a low state. However, when the fuse R0 is cut, the output Out turns to a low state even if the fuse control signal Fuse <0> turns to a high state.
When forming the fuses in a fuse box shape to form the repair address generating circuit, metal signal lines cannot pass over the fuse box. Therefore, the metal signal line should detour around the fuse box for signal routing, and this make a chip size larger.